In the field of art related to the manufacture of color photographic light-sensitive materials, an improvement in sharpness has been required as one of the important means towards improving the color image reproduction, and much research has been undertaken for improving the sharpness.
It is well known that the sharpness of a light-sensitive material is much dependent upon the scattering of light by the silver halide grains it contains and James: The Theory of the Photographic Process, 4th Ed. (1977), pages 580 to 585 states that in the grain size range of 0.6 to 0.4 microns, scattering of light is great with a marked deterioration in sharpness.
Particularly in a multilayer color photographic light-sensitive material comprising red-sensitive, green-sensitive and blue-sensitive layers, the very multilayer structure results in an accumulation of scattered light therein to cause a remarkable decrease in the sharpness of the underlying emulsion layers.
U.S. Pat. No. 3,402,046 describes a method for achieving an improved sharpness which comprises employing relatively coarse grains, at least 0.7 micron, which cause less scattering of light, in the blue-sensitive emulsion layer which is the uppermost emulsion layer of a multilayer color photographic light-sensitive material.
The method described in U.S. Pat. No. 3,658,536 comprises disposing one of two blue-sensitive emulsion layers below a green-sensitive emulsion layer or a red-sensitive emulsion layer for achieiving an improved sharpness.
However, as these methods of necessity employ coarse grains larger than those necessary as blue-sensitive emulsion grains, they have the disadvantage that the graininess of the blue-sensitive emulsion layer is deteriorated.
U.S. Pat. No. 4,439,520 teaches a color photographic light-sensitive material in which the sharpness, sensitivity and graininess have been improved by the use, in at least one of green-sensitive and red-sensitive emulsion layers, of tabular silver halide grains having a thickness of less than 0.3 micron, a diameter of at least 0.6 micron and an average aspect ratio (diameter/thickness) of greater than 8. However, this patent does not show tabular silver halide grains less than 0.6 micron.